src/effects/backends/effectsbackendmanager.cpp:37:29: error: incomplete type ‘EffectManifest’ used in nested name specifier
   37 |             EffectManifest::sortLexigraphically);
      |                             ^~~~~~~~~~~~~~~~~~~

--- mixxx-2.4.0/src/effects/backends/effectsbackendmanager.h
+++ mixxx-2.4.0/src/effects/backends/effectsbackendmanager.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "effects/defs.h"
+#include "effectmanifest.h"
 
 class ControlObject;
 class EffectProcessor;